The Drug Abuse Epidemiology Data Center (DAEDAC) was initiated in November 1973 in order to create a comprehensive archive for research information and original data related to the epidemiological problems of drug abuse. Objectives include (a) Preservation of original data of major surveys and major record sources; (b) Organization of original data files, together with relevant data collection instruments, documentation, reports, and publications, to facilitate further analyses and secondary research that would enable significant contributions based on data available and also to respond to pressing informational needs of administrative agencies in Washington and throughout the country; (c) Development and maintenance of a library of research reports of special interest and concern to medical and social scientists, professionals, working in the drug abuse area; (d) Development of a computer file, with appropriate retrieval software based on a useful taxonomy, to provide bibliographies, statistical tables, and other relevant information on drug abuse problems addressed in the research literature; (e) Organization and integration of drug abuse knowledge by strategic compilations and analyses of accumulated data reports. The intent of the archive is to deal not only with estimates of incidence and prevalence of the use of various drugs of interest in the population, but also with the broad spectrum of factors having putative or demonstrated causal relations with the onset, continued use, transition to other use, dependence patterns, and discontinuance of use of these drugs. As the Center enters its fourth year, utility, quality, and scientific merit, with virtually no restrictions of subject matter of social science relevance to drug abuse, have evolved as primary considerations.